Octopus Biology and Evolution
📌 The term "Octopus" originates from the Greek word for eight, referencing its eight arms (tentacles), and they belong to the Mollusca phylum, similar to squid.
🔬 They are primarily found in the ocean depths, typically near the seabed, though some species live near the surface; tropical water species tend to be smaller than those in cold water.
🥚 Octopuses typically create dens (caves) but move to a new location every 10 to 14 days; some species inhabit debris like bottles on the ocean floor.
🐚 Ancestors of the octopus possessed a hard shell, which gradually disappeared between the Jurassic and Cretaceous periods over 100 to 160 million years, leading to their current boneless structure.

Intelligence and Defense Mechanisms
🧠 Octopuses are highly intelligent, ranking #1 in animal intelligence tests, often surpassing marine mammals in certain aspects, and possess strong problem-solving skills.
💧 For defense, they release a cloud of black ink to confuse predators, allowing them to escape, and can rapidly change their color and texture to camouflage, matching surroundings like stone.
💨 They use a siphon (a muscular tube) to expel water, propelling themselves forward quickly to escape immediate danger.
🔪 If cornered by a persistent predator, the octopus may detach one of its arms; this detached arm can continue to move for at least one hour because each arm has its own control system.

Unique Physiological Features
❤️ Octopuses have three hearts; two pump blood to the gills, and one circulates blood to the rest of the body.
💙 Their blood is blue, not red, because it utilizes a copper-based protein called hemocyanin for oxygen transport, which is more efficient than hemoglobin in low-temperature, low-oxygen environments.
🧠 They possess nine brains (one central brain controlling the nervous system and a small brain in each of the eight arms) allowing the arms to function semi-independently.
🤚 The arms are covered in suckers, each containing about 10,000 neurons, enabling them to perform tasks related to taste and touch locally.

Reproduction and Lifespan
💀 Mating is often fatal for the male, who dies a few months afterward, and the female faces danger from the often larger and hungrier female mate.
🤱 The female lays between 200,000 to 400,000 eggs (depending on the species) and dedicates about seven months to protect them without eating, causing her bodily functions to slow down, leading to death once the babies hatch.
⏳ The lifespan of an octopus is generally very short; some species live only six months, while larger species like the North Pacific Giant Octopus can live up to 5 years.

Key Points & Insights
➡️ The octopus's lack of an internal skeleton allows it to squeeze its large body into very small spaces, constrained only by the size of its beak (mouth part), which resembles a parrot's.
➡️ Their arms possess significant autonomy, containing two-thirds of their neurons, allowing them to independently coordinate movement, problem-solving, and reaction.
➡️ Octopuses generally avoid prolonged swimming because the heart responsible for circulating blood to the organs stops beating during swimming, leading to rapid exhaustion.

📸 Video summarized with SummaryTube.com on Dec 30, 2025, 15:36 UTC